Surgical Instruments including Expandable Electrodes and Methods for Ablating Tissue in a Patient with the Surgical Instruments

Abstract

An example surgical instrument includes an insulated shaft, and an expandable electrode at a distal end of the insulated shaft. The expandable electrode includes a shape memory alloy lattice. Based on passing electrical current through the shape memory alloy lattice, the shape memory alloy lattice undergoes a shape memory transition from a non-expanded configuration to an expanded configuration causing the expandable electrode to radially expand outward in diameter.

What is claimed is: 
     
         1 . A surgical instrument, comprising:
 an insulated shaft; and   an expandable electrode at a distal end of the insulated shaft, wherein the expandable electrode comprises a shape memory alloy lattice, and based on passing electrical current through the shape memory alloy lattice, the shape memory alloy lattice undergoes a shape memory transition from a non-expanded configuration to an expanded configuration causing the expandable electrode to radially expand outward in diameter.   
     
     
         2 . The surgical instrument of  claim 1 , wherein the shape memory alloy lattice is a pre-formed nitinol lattice. 
     
     
         3 . The surgical instrument of  claim 1 , wherein based on removal of the electrical current from the shape memory alloy lattice, the shape memory alloy lattice returns to the non-expanded configuration. 
     
     
         4 . The surgical instrument of  claim 1 , wherein based on passing the electrical current through the shape memory alloy lattice, a temperature of the shape memory alloy lattice increases causing the shape memory transition. 
     
     
         5 . The surgical instrument of  claim 1 , wherein the expandable electrode has a length of about 100 mm. 
     
     
         6 . The surgical instrument of  claim 1 , wherein the expanded configuration of the expandable electrode has an outer diameter of about 1.65 mm. 
     
     
         7 . The surgical instrument of  claim 1 , wherein the non-expanded configuration of the expandable electrode has an outer diameter of about a 22 gauge needle. 
     
     
         8 . The surgical instrument of  claim 1 , wherein the expanded configuration of the expandable electrode has an outer diameter of about a 16 gauge needle. 
     
     
         9 . The surgical instrument of  claim 1 , wherein the expanded configuration of the expandable electrode includes:
 a first tapered section coupled to the insulated shaft;   a second tapered section at a distal tip; and   a substantially cylindrical section between the first tapered section and the second tapered section.   
     
     
         10 . The surgical instrument of  claim 1 , wherein the expandable electrode has a flexible tip. 
     
     
         11 . The surgical instrument of  claim 1 , wherein the insulated shaft comprises a conductor with insulation enabling conduction of the electrical current from a proximal end of the insulated shaft to the expandable electrode at the distal end of the insulated shaft. 
     
     
         12 . The surgical instrument of  claim 1 , wherein the insulated shaft comprises a conductor and the expandable electrode is formed at the distal end of the conductor, such that the insulated shaft and the expandable electrode are formed on the same conductor. 
     
     
         13 . The surgical instrument of  claim 1 , wherein the shape memory alloy lattice comprises:
 a plurality of geometric unit cells repeated in circumferential and axial directions.   
     
     
         14 . A surgical equipment, comprising:
 an introducer;   a surgical instrument inserted into the introducer, wherein the surgical instrument comprises:
 an insulated shaft; and 
 an expandable electrode at a distal end of the insulated shaft, wherein the expandable electrode comprises a shape memory alloy lattice, and based on passing electrical current through the shape memory alloy lattice, the shape memory alloy lattice undergoes a shape memory transition from a non-expanded configuration to an expanded configuration causing the expandable electrode to radially expand outward in diameter. 
   
     
     
         15 . The surgical equipment of  claim 14 , wherein:
 the surgical instrument is selectively translatable relative to the introducer between a proximal retracted position in which the expandable electrode is housed within the introducer to a distal extended position in which the expandable electrode is exposed from the introducer to permit the expandable electrode to radially expand from the non-expanded configuration to the expanded configuration.   
     
     
         16 . The surgical equipment of  claim 14 , further comprising:
 a power source coupled to the surgical instrument to provide the electrical current to the expandable electrode.   
     
     
         17 . A method of ablating tissue in a patient with a surgical instrument, comprising:
 inserting a trocar needle through an introducer and into the patient allowing the introducer to be positioned adjacent to a target area;   removing the trocar needle from the introducer;   inserting the surgical instrument into the introducer, wherein the surgical instrument comprises an insulated shaft and an expandable electrode at a distal end of the insulated shaft, wherein the expandable electrode comprises a shape memory alloy lattice;   exposing the expandable electrode relative to the introducer causing the expandable electrode to protrude out from the introducer;   applying electrical current to pass through the shape memory alloy lattice of the expandable electrode to cause the shape memory alloy lattice to undergo a shape memory transition from a non-expanded configuration to an expanded configuration so that the expandable electrode radially expands outward in diameter; and   contacting the tissue with at least a portion of the expandable electrode exposed from the introducer while in the expanded configuration.   
     
     
         18 . The method of  claim 17 , wherein the expandable electrode receives the electrical current and generates heat, and wherein based on contacting the tissue with the portion of the expandable electrode exposed from the introducer while in the expanded configuration results in forming a lesion circumferentially along a body of the expandable electrode. 
     
     
         19 . The method of  claim 17 , further comprising:
 detecting a temperature of the expandable electrode with a thermistor; and   based on the temperature being above a threshold, discontinuing application of the electrical current to the shape memory alloy lattice.   
     
     
         20 . The method of  claim 17 , further comprising:
 after said contacting, discontinuing application of the electrical current to the shape memory alloy lattice to cause the shape memory alloy lattice to transition from the expanded configuration to the non-expanded configuration.